ASTM A403 WP347-WX Stainless Steel Pipe Fitting ASME B16.9 Buttweld Equal Tee
ASTM A403 / ASME SA403 WP347-WX Equal Tee, Stainless Steel Buttweld Pipe Fitting
The specification ASTM A403 is standard in the chemical, petrochemical, and power generation industries where resistance to intergranular corrosion after welding or exposure to high temperatures is required. WP347 Buttweld Tee is a high-chromium, nickel, columbium-stabilized stainless steel pipe fitting. It is designed to be welded into a piping system and is specifically engineered to resist corrosion and maintain strength in high-temperature environments that would cause standard 304 stainless steel to fail.
ASTM A403 WP347-WX Stainless Steell Pipe Fitting Buttweld Tee Equivalent Grades
| STANDARD | WERKSTOFF NR. | UNS | JIS | GOST | EN |
| SS 347 | 1.4550 | S34700 | SUS 347 | 08Ch18N12B | X6CrNiNb18-10 |
| SS 347H | 1.4961 | S34709 | SUS 347H | – | X6CrNiNb18-12 |
ASTM A403 WP347-WX Stainless Steell Pipe Fitting Buttweld Tee Chemical Composition
| Element % | 347 | 347H |
| Chromium | 17.00 min.-19.00 max. | 17.00 min.-19.00 max. |
| Nickel | 9.00 min.-13.00 max. | 9.00 min.-13.00 max. |
| Carbon | 0.08 | 0.04 min.-0.10 max. |
| Manganese | 2 | 2 |
| Phosphorus | 0.045 | 0.045 |
| Sulfur | 0.03 | 0.03 |
| Silicon | 0.75 | 0.75 |
| Columbium & Tantalum | 10 x (C + N) min.-1.00 max. | 8 x (C + N) min.-1.00 max. |
| Iron | Balance | Balance |
ASTM A403 WP347-WX Stainless Steell Pipe Fitting Buttweld Tee Mechanical Properties
| Grade | 347 / 347H |
| Tensile Strength (MPa) min | 515 |
| Yield Strength 0.2% Proof (MPa) min | 205 |
| Elongation (% in 50mm) min | 40 |
| Rockwell B (HR B) max | 92 |
| Brinell (HB) max | 201 |
Heat Treatment Requirements
This is the most critical part of the specification. SS347 is a stabilized grade, the heat treatment (if required) differs slightly from standard 304.
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Solution Annealing (Required for cold worked fittings):
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Temperature: Heat to a minimum of 1900°F (1040°C) .
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Quenching: Rapid cooling (water quenching or rapid air cool) is required.
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Why? To dissolve any chromium carbides that may have formed and to put the Columbium into a state where it can effectively stabilize the structure.
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Stabilization Annealing (Optional but beneficial):
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Sometimes, fittings are given an additional heat treatment at 1550°F to 1650°F (843°C - 899°C). This allows the Columbium to fully "find" and combine with the Carbon, ensuring maximum resistance to intergranular corrosion in severe service.
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Applications
- Chemical Processing Plants: Handling nitric acid, and other chemicals where sensitization leads to rapid failure.
- Refineries: High-temperature hydrocarbon service.
- Power Generation: Boiler components, superheater tubes, and steam lines operating at high temperatures.
- Aerospace: Exhaust manifolds and engine components.
- Food Processing: Equipment requiring sterilization at high temperatures.
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